There was nothing out of the ordinary about the young man clutching a sheaf of papers at the birth certificate office, except for his name: Saddam Hussein al-Majid.

“All three of your names match his,” the clerk at the desk said with a laugh, referring to Iraq's deposed leader. “That's unbelievable!”

Mr. Hussein shrugged in exasperation. “What can I do?” he said. His parents had chosen the name, not he.

Now he was trying to avoid paying with his life for that decision. He wanted to change the first name on his birth certificate to Sajad, favored by Shiites. Mr. Hussein, a Shiite Arab, was all too aware that militiamen from his own sect might assume he belonged to the former ruling Sunni Arab minority.

The man in line behind him, another Saddam, wanted to change his name to Jabar, one of Islam's 99 names for God.

The country's Sunni-Shiite bloodletting is driving many Iraqis to bury the very essence of their identity: their names.

To have to hide one's name is considered deeply shameful. But with sectarian violence surging, Iraqis fear that the name on an identification card, passport or other document could become an instant death sentence if seen by the wrong people.

That is because some first names and tribal names indicate whether a person is Sunni or Shiite. A first name of Omar is popular among Sunnis, for example, as is Ali among Shiites.

Stories abound of Iraqi civilians being stopped at checkpoints by militiamen, insurgents or uniformed men and having their identification cards scrutinized. They are then taken away or executed on the spot if they have a suspect name or a hometown dominated by the rival sect. In Baghdad, Shiite death squads — sometimes in police uniform — operate many of the illegal checkpoints, Iraqi and American officials say.

The most infamous episode of this kind took place in July, when Shiite gunmen set up fake checkpoints and went on a daytime rampage through the Jihad neighborhood of Baghdad, dragging people from their cars and homes and shooting them after looking at their identification cards. Up to 50 people were killed.

In the first seven months of this year, 1,000 Iraqis officially changed their names, far more than in any similar period since the American invasion of 2003, said Maj. Gen. Yaseen Tahir al-Yasiri, director of the Interior Ministry department that issues identity documents. Most were Sunni Arabs. The rush began after the bombing of a revered Shiite shrine in Samarra last February set off waves of sectarian violence.

Forgers of identification cards say business is booming. Every Iraqi is issued a national ID card, called a gensiya. A forger in the Shiite slum of Sadr City who calls himself Abu Ahmed said he makes six or seven fake cards a day, mostly for people who want sect-neutral names. He is not proud of helping people mask their identity and their sect. “We do these things and we're ashamed of it,” he said.

The growing number of people seeking to change or hide their names is just one consequence of the enormous fear that Iraqis now have of revealing their sect. More and more, Iraqis are asking themselves whether their sectarian allegiance is obvious to those around them, and if so, how to cover it up.

There is no way to physically tell Sunni Arabs from Shiite Arabs, so militiamen and insurgents are increasingly killing people based on small, telltale signs — whether the owner of a car or a house has posters or stickers of Shiite martyrs, for instance, or whether a driver has a car with a license plate from a Sunni-dominated province.

Before the Samarra bombing, Abu Ahmed's business generally came from parents who wanted to change their children's ages so they could start elementary school early. He made only 25 to 40 cards a month.

Now, his clients include people who simply want to commute between the Sunni enclave of Adhamiya and the neighboring Shiite bastion of Kadhimiya without being harassed at militia or police checkpoints, Abu Ahmed said. He charges anywhere from $7 to $50 for a new ID card.

First names that are particular to Sunnis or Shiites usually pay homage to leaders in the 7th century who played important roles in the split between the sects.

Common names among Shiites include Ali, Hussein and Abbas. Sunnis prefer Omar, Othman or Marwan. The tribal name can also be a giveaway — Dulaimi and Jubouri are large Sunni tribes, for example, while Lami and Daraji are predominantly Shiite ones.

Ahmed and Muhammad are favorite neutral names for those seeking new names or fake ID cards.

General Yasiri, the government official, said that when he signed documents approving name changes, “my hand shakes, because these names are not dirty or nasty names. Sometimes I tell the people to be patient and not to change their names. But they say, ‘Sir, we can't, because we're facing a very dangerous situation.' ”

Many residents of Falluja, an insurgent stronghold in the Sunni-dominated province of Anbar, have bought fake ID cards to hide their names and hometown in case they have to travel to Baghdad or other mixed areas.

Bassim Abdullah Farhan, 40, the owner of an automotive parts shop, said he paid the equivalent of $35 for a fake ID that lists his tribal name as Shammari rather than Dulaimi, and his hometown as Baghdad rather than Falluja. “We never expected that the scale of killings and evictions would be so large and so violent,” he said as he sipped tea outdoors with a friend.

An American official in Falluja said that Sunni Arab families fleeing persecution in Baghdad asserted that the “scarlet ‘A' for Anbar equals death” if militant Shiites spot it on an ID card.

Driving with an Anbar license plate can be just as dangerous. Iraqis tell stories of Shiite militiamen gunning down or abducting drivers with Anbar plates.

Abdullah Ali, a mechanic in Baghdad, said he watched as his brother-in-law was recently pulled from a car with Anbar plates by gunmen in the Shiite neighborhood of Shuala. The brother-in-law, Marwan Najim Abdullah, from Falluja, had been driving his white Buick sedan as part of a wedding convoy. The gunmen zeroed in on Mr. Abdullah's car, apparently because of its plates.

“His family collected him from the morgue,” Mr. Ali said.

Mr. Ali said he also had a cousin who had been kidnapped, mutilated and shot dead in Shuala because he had the wrong license plates. The cousin, a cabby, had driven into the neighborhood in a Volkswagen Passat with plates from Sunni-dominated Salahuddin Province. But the Shiite militiamen who killed him made a horrible mistake, Mr. Ali said — the cousin was a Shiite who happened to have Salahuddin plates.

The human rights office of the leading Sunni Arab political group, the Iraqi Islamic Party, has received dozens of reports of civilians being harassed or killed because of their license plates, said Yahia Ghazi Abdul Latif, an employee in the office. In June, for instance, the party heard of 10 such episodes, he said. They usually occur at checkpoints set up by militiamen or Interior Ministry commandos, he added.

“I had a car with Anbar plates myself, and I sold it for this very reason,” Mr. Abdul Latif said. “I didn't even sell it for a good price.”

An Interior Ministry spokesman denied that policemen or commandos were discriminating based on license plates.

A market for fake license plates has sprung up, just like the one for fake ID cards. And the demand for cars with Anbar and Salahuddin plates has plummeted, since changing the original plates involves bureaucratic hassle. Abdul Sattar al-Taie, a car dealer in Baghdad, said he had had to mark down cars with those plates by 20 percent.

“The changing market is due to sectarian violence,” Mr. Taie said with a sigh.

“The Iraqis are one people, from north to south and south to north,” he added. “There is no discrimination.”